Stacked Image Sensor Auto-Focusing Resolution Trade-off
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Solution Overview
Problem
Existing camera image sensors face a trade-off between auto-focusing capabilities and image resolution, as replacing some image sensors with AF sensors reduces the overall resolution due to the hybrid AF method's need for both phase and contrast detection, which slows down focusing speed and diminishes image quality.
Innovation Solution
A stacked image sensor design incorporating multiple photoelectric conversion regions and color filters, with specific regions dedicated to auto-focusing and image detection, utilizing barriers and micro-lenses to enhance light management and prevent noise, allowing for simultaneous high-resolution image capture and auto-focusing without reducing pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If some image sensors are replaced by AF sensors in a hybrid AF method, then auto-focusing capability is improved, but image resolution is reduced
Solution Approach 1:
The patent transitions from a planar arrangement where AF sensors replace image sensors to a three-dimensional stacked architecture. The first photoelectric conversion layer contains AF regions while the second layer contains full image sensor regions, allowing both functions to coexist without spatial trade-off. This vertical dimensionality change resolves the contradiction by enabling simultaneous high-resolution imaging and auto-focusing capability.
Solution Approach 2:
The image sensor is segmented into multiple functional layers: the first photoelectric conversion layer is divided into image sensor regions and AF regions, while the second photoelectric conversion layer is dedicated to image sensing. This segmentation allows different regions to perform different functions simultaneously, resolving the contradiction between maintaining full image resolution and providing auto-focusing capability.
2Adaptability or versatility
If some image sensors are replaced by AF sensors, then phase detection AF is enabled, but the number of pixel regions is reduced
Solution Approach 1:
The patent moves the AF function to a separate layer (first photoelectric conversion layer) while keeping the second layer dedicated to image sensing. This vertical separation allows phase detection AF to be enabled without reducing the quantity of pixel regions in the image sensor layer, as both functions operate in different spatial dimensions.
Solution Approach 2:
The first photoelectric conversion layer serves dual purposes: it provides phase detection AF capability through dedicated AF regions while also contributing to image sensing through its image sensor regions. This multi-functionality enables the system to achieve both phase detection and maintain pixel quantity without compromise.
3Measurement precision
If hybrid AF method uses both phase and contrast detection, then focusing accuracy is improved, but focusing speed is reduced
Solution Approach 1:
The stacked architecture enables preliminary phase detection AF to be performed rapidly using the first photoelectric conversion layer's AF regions. Once a preliminary focus is achieved, contrast detection AF can be applied for fine-tuning. This preliminary action approach maintains high focusing speed while achieving accurate focus through the combination of both methods.
Solution Approach 2:
The focusing process is segmented into two stages: rapid phase detection AF using the first layer's AF regions for initial focus acquisition, followed by contrast detection AF for fine-tuning. This segmentation of the focusing process allows the system to maintain high speed during the primary focusing phase while achieving high accuracy through the secondary refinement phase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables high-resolution image capture during auto-focusing, maintaining image quality even under high illumination conditions by utilizing all pixel regions effectively for both image detection and focusing, while preventing light interference and noise.
Implementation Method 1
a first photoelectric conversion layer including a plurality of first photoelectric conversion regions; a second photoelectric conversion layer disposed on the first photoelectric conversion layer, and including a plurality of second photoelectric conversion regions
Implementation Method 2
a plurality of color filters disposed on the plurality of second photoelectric conversion regions
Implementation Method 3
first barriers that separate the plurality of pixel regions from one another and vertically pass through the second photoelectric conversion layer and the first photoelectric conversion layer
Data Source
AI summary
A stacked image sensor includes a first photoelectric conversion layer including a plurality of first photoelectric conversion regions; a second photoelectric conversion layer disposed on the first photoelectric conversion layer, and including a plurality of second photoelectric conversion regions; and a plurality of color filters disposed on the plurality of second photoelectric conversion regions, wherein at least one of the plurality of first photoelectric conversion regions includes a plurality of third photoelectric conversion regions that perform auto-focusing.